Head-mounted display devices (HMDs) are known in the art. Such devices include so-called ‘smart glasses’, which allow the wearer thereof to visualize information content such as images or text for augmented reality.
When wearing such head-mounted device, the wearer may find himself/herself in situations of ‘dual’ visualization. Namely, the wearer may wish to look at a ‘real’ object from the environment (for example, a monument or a traffic sign) and at a virtual display provided/generated by the HMD (for example, information about the monument or driving directions). Thus, the wearer should be able to switch rapidly and comfortably between the visualization of the ‘real’ world (environment of the wearer) and the visualization of the ‘virtual’ display provided by the HMD. Therefore, the HMD should be designed in such a way that minimal accommodation efforts are required for the wearer in such situation.
EP0716329A1 discloses a HMD wherein the display system can be adjusted so as to set the visualization distance of the virtual image. The proximity of the virtual display and that of the ‘real’ display are always the same. This system is inconvenient for the wearer, since it requires constant adjustment. Further, it lacks flexibility in that it does not contemplate situations wherein the ‘distance’ to the virtual display differs from that of the ‘real’ object visualized by the wearer.
According to the invention, the HMD can be optimized so that the wearer can comfortably switch from a ‘real’ visualization (that can be one or more objects in one or more of the following vision fields: far vision, near vision, intermediate vision) to a ‘virtual’ visualization (that can be at a set/fixed virtual distance of visualization, which occurs for example if the HMD comprises a LOE; or not set/fixed, as is the case for adjustable/settable systems) and vice-versa. Further, according to the present invention, the display HMD may be customized to the wearer.